RE: [boost] Explicit instantiation of boost::shared_ptr<SomeClasss>

From: Greg Clayton (Greg.Clayton_at_[hidden])
Date: 2004-03-15 12:01:42

> -----Original Message-----
> From: Peter Dimov [mailto:pdimov_at_[hidden]]
> Sent: Friday, March 12, 2004 12:24 PM
> To: boost_at_[hidden]
> Subject: Re: [boost] Explicit instantiation of
> boost::shared_ptr<SomeClasss>
> 
> 
> Greg Clayton wrote:
> >> -----Original Message-----
> >> From: Peter Dimov [mailto:pdimov_at_[hidden]]
> >> Sent: Thursday, March 11, 2004 4:48 PM
> >> To: boost_at_[hidden]
> >> Subject: Re: [boost] Explicit instantiation of
> >> boost::shared_ptr<SomeClasss>
> >>
> >>
> >> Greg Clayton wrote:
> >>> I am trying to do explicitly instantiate specific shared_ptr class
> >>> for export from a Win32 DLL (currently with MSVC6, and 
> eventually in
> >>> VS2003).
> >>
> >> First things first. Why do you need to do that? Have you
> >> tried not exporting it, have you encountered any problems?
> >
> > Yes, shared pointers can't be created and handed off from DLL to DLL
> > the way they are currently implemented. If DLL A has an STL 
> container
> > of shared pointers, and DLL B gets _dynamically_ loaded and adds an
> > item to DLL A's container (creates a shared pointer to an 
> object, and
> > DLL B adds that shared pointer through an interface it to 
> DLL A's STL
> > container of shared pointers), DLL B can not be unloaded. If DLL B
> > does get unloaded you will crash when your STL container goes out of
> > scope (when it tries to delete the owned pointer).
> 
> Isn't it possible for the DLL C that contains the definition 
> of SomeClass to
> export
> 
>     shared_ptr<SomeClass> createSomeClass();
> 
> which DLL B can now call when it needs a SomeClass?
> 
> Since ~SomeClass lives in C, it must be available when the last
> shared_ptr<SomeClass> is destroyed.
> 

This was my initial solution, and it does work. Though I was searching for the ability to just create a shared pointer anywhere and had it to any other DLL by exporting the entire shared pointer instantiation from the main DLL.